Receiver



Junge 6, 1933. J. BETHENQD v"1,912,752

RECEIVER Filed April 25, 1929 .INVENTOR JOSEPH simens ,I

ATTORNEY Patented June 6, 1933 1,912,752

UNITED stares PATENT oFFicE JOSEPH IBETHE'NOD, OF PARIS, FRANCE RECEIVER Application filed April 26, 1929, Serial No. 358,310, and in France April 26, 1928.

This'invention relates broadly to improVe- The invention will be more easily underments 1n radio broadcast recelyers and espestood by referring to the drawing which .clally to a system for controlling the signal shows a single preferred embodiment of the intensity or volume thereof. invention. This scheme is in its extent, sim- 5 ,More specifically the present invention is ilar to that of Figure 2 in application Serial 55 directed to correcting approximately the'un- No. 355,083 already referred to, but varied desirable changes of amplitude known as fadby using two-grid tube prior to the detector ing, in receivers, wherein potential variaand connected to a resonant circuit posterior' tions due to flowing of the detected current in to the dtector.` a. resistance posterior to the detector, are fed The oscillations flowing to O from the anto grids of one orseveral tubes prior to said tenna excite a resonator 1 comprising the detector. coil 2 and the capacity 3. The said resona- These potential variations change the sentor is connected between the inner grid 21 sitivity of the receptor in opposite sense to and the cathode of the two-grid tube 20. the intensity of received oscillations. The plate circuit of that tube Ltransmits the It has already been proposed in U. S. aposcillations to the tube 7, from there to the plication Serial No, 355,083 of H. J. J. M. de amplifier 8, in fact any amplifier device (fre- R. de Bellescize, to realize the aim and scope qucncy-changer, two-grids from there of this invention by means of increasing the to the detector tube 9. The low-frequency time constant of the resistance capacity ciramplifying unit is provided with stages 1.4 T9 cuit provided for controlling the sensitivity and 19, connected together and with the priprior to the detector, in order that changes in or stages by way of the unction batteries 3l signal amplitude, will not cause noticeable and 17. rlhe indicating or registrating appotential variations at an extremity of the paratus is shown generally as 2G. The cirresist-ance incorporated in said circuit. That cuit with a high time constant including a circuit is placed to the end of the receptor, resistance l0 and one of the capacities 11 hence energically acting on a unit anterior to 1lb, llc, interchangeable by means of a comthe detector. inutator device, is placed to end of receptor The present invention .has for its object to and disjoined from the plate of the last tube indicate that the unit placed before the ainpliby a high frequency blocking condenser 25. 80 fier may be a twoegrid tube. The potential The polarization battery 12 with a varivariations created in the resistance passed by able tap 28 is connected to said circuit. The the detected current are fed to the outer grid tap is united to the outer grid of the bigrid of the tube, across a` polarization source and, tube 20 across a i regulable condenser 24 a regulable condenser shunted by a resistance. shunted by a resistance `23. 35 The incoming oscillations are applied berlho batteries 27 feed filament, grids and y tween the inner grid and the cathode of the plates of the system. two-grid tube; the plate is united to the de- I claim: tector, if necessary, by way of any amplifier A receiving circuit comprising` a radio fresystem, and particularly one or several twoquency amplifier including a multi-grid tube, grid tubes comprising the foregoing arrangea detecting circuit coupled to said radio freinents. 'In this way, the sensitivity of that `quency amplifier and an audio frequency amplification can be regulated prior to detecamplifier coupled to said. detecting circuit, an tion in accordance with the strength of the indicator device coupled to the output of said detected signal. audio-frequency amplifier, a circuit having a 95 It is moreover possible to transpose or exrelatively high time constant comprising a change the parts played by the inner and outresistance and a capacity adapted to have a er grid by a suitable choice of the polarizacurrent proportional in intensity to the intion potentials series in the lead brought to tensity of the detected current flow therethe resistance passed by the detected current. through for causing variations of potential across said resistance in accordance with the intensity ot the detected current and a connection including a capacity and a source of current in series between said high time constant circuit and one of the grids of said tube for Varying the sensitivity of said radio frequency alnpliiier in accordance With said potential variations set up across said resistance and means for impressing incoming signal currents upon another grid of said tube.

JOSEPH BETHENOD. 

